The invention relates to footwear or shoes, particularly walking or athletic shoes.
Footwear can be designed to provide a variety: of stylistic and functional benefits. A particular functional benefit is the comfort of the wearer of the shoe. Particularly when walking or running, the flexibility and shock absorption of the shoe determine the amount of comfortable support provided to the feet of the shoe wearer.
Shoes normally worn for active use, e.g., extensive walking or fitness sports, typically consist of an upper (of canvas, leather or other supple fabric material) joined to an outer sole (of rubber, leather or other durable material) having a bottom that contacts the ground. The inner surface of the outer sole, i.e., outsole, has distinct regions that contact corresponding portions of the wearer""s foot sole. For example, the outsole can have distinct heel, arch and plantar regions that underlie the respective portions of the foot. These regions of the outsole can be specifically adapted to provide functional benefits to the parts of the foot that are supported by them. A highly flexible inner sole, i.e., insole, is usually provided that directly contacts the wearer""s foot and is positioned between the foot and the upper surface of the outsole. The insole has an upper surface of fabric or soft leather to give added comfort and breathability to the sole of the foot. The outsole needs to embody both flexible and durable characteristics, to resist wear from pavement and torsional stresses, also to cushion shock from impact due to foot motion.
Others in the art have sought to provided added shock absorption to the outsole by providing added layers or members in various regions of the outsole. For example, U.S. Pat. No. 4,783,910 to Boys, II et al., provides a midsole with a discrete heel capsule to cushion G-forces, in conjunction with an anti-torsion heel member. U.S. Pat. No. 1,994,681 to Bliinifeld, U.S. Pat. No. 4,245,406 to Landay, et al., and U.S. Pat. No. 5,839,208 to Huang disclose outsoles having inner cavities presenting patterns of ribbed structures that are joined to the sides of the outsole. Such structures are said to enhance the shock-absorbing support function of the outsole and its torsional stability.
U.S. Pat. No. 4,794,707 to Franklin, et al., shows a midsole with an internal dynamic rocker element disposed in the forefoot of the midsole, said to enhance walking comfort.
U.S. Pat. No. 4,663,865 to Telecemian has a first set of ribs that extend from within the heel cavity and a second set of ribs extending diagonally through the arch cavity, both sets dovetailing into the floor of the plantar cavity. A resilient cushion is located in the plantar cavity, being shaped and sized corresponding to that cavity. However, the separate cushion does not form an integral part of the inner-plantar cavity of the outsole, but rather functions as an integral component of the midsole than of the outsole. Moreover, such a cushion requires additional steps to assemble together with the midsole during the manufacturing process.
Therefore it is desirable to provide a strategically positioned cushioning support member in a strategic functional region of the outsole activity, which member functions integrally with the outsole in cushioning shock to a given area of the foot of the shoe wearer.
It is further desirable to-provide a cushioning member that is fabricated as part of the inner cavity of the outsole, so that the member is joined thereto and functions integrally with the outsole, versus other components of the shoe during wear.
It is still further desirable to provide an integral cushioning member that functions together with other stabilizing members found within the inner cavity of the outsole.
The invention advantageously provides enhanced support of the foot wearing a shoe according to the invention, while eliminating unnecessary manufacturing steps. An upper sole, an insole, and an outsole are provided, to manufacture a shoe according to the invention. The outsole comprises a heel, an arch, and a plantar region. A cavity is formed in one or more of the heel, arch and plantar regions of the outsole. A cushioning pad is permanently affixed in the cavity. The upper sole, insole and outsole are then assembled to make the shoe according to the invention. The pad functions integrally with the outsole in cushioning shock to a given area of the foot wearing the shoe. A midsole and the manufacturing process for making the same are no longer needed as a result.
In a preferred embodiment of the invention, the outsole is made of a flexible polymeric material having a given density and the pad is molded in place within the plantar region, the pad being formed of a different polymeric material than the outsole, such that the plantar and heel regions are of differing densities, respectively.
In other embodiments of the invention, injection molding is used to mold the insole and the outsole (with the cushioning pad attached) into a bonded insole/outsole in a single molding step. Alternatively, injection molding is used to mold the upper sole, the insole, and the outsole in a single molding step, depending on manufacturing requirements. A further advantage of the invention is the flexibility of selecting a molding process suitable for the particular manufacturing situation.
In a further embodiment of the invention, the cavity is defined by a plurality of ribs (made of, e.g., thermal plastic rubber or TPR) integrally formed on the peripheral wall of the outsole. The cushioning pad (made of, e.g., ethyl vinyl acetate or EVA) is placed in the cavity as defined by the ribs. The peripheral wall and bottom of the outsole are molded in a first stage. The cushioning pad is made separately. The ribs are then molded in a second stage. The cushioning pad is permanently affixed by adhesion to the top surface of the bottom of the outsole in the cavity and to the surrounding ribs after the ribs are molded. In an alternative embodiment of the invention, the ribs are molded while the cushioning pad is in place in the cavity of the outsole.
In yet another preferred embodiment of the invention, a plurality of ribs form a structure defining a series of combs that articulate with the peripheral wall of the outsole, the arrangement further delimiting an inner periphery of the cavity, wherein the pad is joined to that inner periphery. In a further preferred embodiment, the cavity and pad are shaped to correspond to the contours of the peripheral walls of the outsole.
In an additional embodiment of the invention, a plurality of ribs form a structure defining a series of open combs that extends transversely across the outsole and articulates with the peripheral wall of the outsole within one or more of the heel, arch and plantar regions. It is further preferred that the pad be molded in place within the combs of the plantar region.
An advantage of the invention is that a strategically positioned cushioning support pad can function in a strategic region of the outsole, as an integral part of the outsole, in cushioning shock to a given area of the foot wearing a shoe according to the invention.
Another advantage of the invention is that the cushioning pad can be fabricated as part of the cavity of the outsole, so that the pad is joined thereto and functions integrally with the outsole, versus other components of the shoe during wear.
Yet another advantage of the invention is an integral cushioning pad that functions together with other stabilizing members (e.g., ribs) found within the cavity of the outsole.
A further advantage of the invention is enhanced support and shock absorption by providing an outsole with selected cushioning capacity where needed, without the necessity of a separately engineered midsole.